CVE-2026-77391 Overview
CVE-2026-77391 is a cross-site request forgery (CSRF) vulnerability affecting SourceCodester Dynamic Input Field Generator Using HTML, CSS, and PHP 1.0. An unknown function in the application accepts state-changing requests without validating their origin. Attackers can trigger the flaw remotely by tricking an authenticated user into visiting a crafted page or link. Public exploit code has been released, increasing the likelihood of opportunistic abuse against exposed deployments. The weakness is tracked as CWE-352: Cross-Site Request Forgery.
Critical Impact
Remote attackers can perform unauthorized actions on behalf of authenticated users by leveraging released proof-of-concept exploit code, with user interaction required for exploitation.
Affected Products
- SourceCodester Dynamic Input Field Generator Using HTML, CSS, and PHP 1.0
Discovery Timeline
- 2026-08-21 - CVE-2026-77391 published to NVD
- 2026-08-24 - Last updated in NVD database
Technical Details for CVE-2026-77391
Vulnerability Analysis
The vulnerability resides in the SourceCodester Dynamic Input Field Generator Using HTML, CSS, and PHP 1.0 web application. A state-changing endpoint processes requests without verifying that the request originated from a trusted source. Because the application relies solely on ambient session credentials such as cookies, any authenticated browser session can be coerced into submitting attacker-controlled requests. Public proof-of-concept code has been released, lowering the barrier for practical exploitation against internet-facing installations. The VulDB entry for CVE-2026-77391 provides additional context on the affected component.
Root Cause
The root cause is the absence of anti-CSRF protections on a sensitive request handler. The application does not issue or validate synchronizer tokens, does not check the Origin or Referer headers, and does not require re-authentication for privileged operations. Without these controls, the browser automatically attaches session cookies to any request the user is tricked into making.
Attack Vector
Exploitation requires an authenticated victim to interact with attacker-supplied content, such as a malicious webpage, email link, or embedded form. Once the victim's browser is loaded with the attacker's payload, it silently issues a forged request to the vulnerable endpoint. The server processes the request as if it were legitimate, executing the action associated with the victim's session. A public proof of concept is available.
Detection Methods for CVE-2026-77391
Indicators of Compromise
- Unexpected state changes in application data tied to authenticated user sessions with no corresponding user activity.
- HTTP requests to the vulnerable endpoint with Referer or Origin headers pointing to untrusted external domains.
- Cluster of identical POST or GET requests originating from browser sessions shortly after users clicked external links.
Detection Strategies
- Instrument web server or WAF logs to flag state-changing requests missing a valid same-origin Referer header.
- Correlate authentication session identifiers with request origins to spot requests initiated from third-party pages.
- Review application audit logs for administrative or configuration changes not initiated through the standard user interface.
Monitoring Recommendations
- Forward web server, reverse proxy, and application logs to a centralized analytics platform for correlation.
- Alert on spikes of POST traffic to configuration endpoints without prior GET requests loading the associated form.
- Track user reports of unexpected changes to their accounts or application state as a leading indicator of active CSRF abuse.
How to Mitigate CVE-2026-77391
Immediate Actions Required
- Restrict access to the SourceCodester Dynamic Input Field Generator instance to trusted internal networks until remediation is applied.
- Require users to log out of the application when finished and avoid browsing untrusted sites in the same session.
- Deploy a web application firewall rule to block cross-origin state-changing requests to the affected endpoints.
Patch Information
No vendor patch has been referenced for CVE-2026-77391 at the time of publication. Monitor the SourceCodester website and the VulDB advisory for updates. Organizations that maintain the source themselves should implement synchronizer token protection and origin verification on all state-changing handlers.
Workarounds
- Add anti-CSRF tokens to every form and validate them server-side before processing state-changing requests.
- Set session cookies with the SameSite=Strict or SameSite=Lax attribute to prevent cross-site cookie transmission.
- Validate the Origin and Referer headers on sensitive endpoints and reject requests from unexpected sources.
- Require re-authentication or a secondary confirmation step for privileged actions within the application.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
